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Photosensitive Melanopsin-Containing Retinal Ganglion Cells in Health and Disease: Implications for Circadian Rhythms

Department of Physiology, Genetics and Microbiology, University of Alicante, 03690 Alicante, Spain
Department of Optics, Pharmacology and Anatomy, University of Alicante, 03690 Alicante, Spain
Department of Ophthalmology, University of Murcia, 30120 Murcia, Spain
Multidisciplinary Institute for Environmental Studies “Ramon Margalef”, University of Alicante, 03690 Alicante, Spain
Author to whom correspondence should be addressed.
Int. J. Mol. Sci. 2019, 20(13), 3164;
Received: 16 May 2019 / Revised: 26 June 2019 / Accepted: 26 June 2019 / Published: 28 June 2019
(This article belongs to the Special Issue Retinal Ganglion Cells)
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Melanopsin-containing retinal ganglion cells (mRGCs) represent a third class of retinal photoreceptors involved in regulating the pupillary light reflex and circadian photoentrainment, among other things. The functional integrity of the circadian system and melanopsin cells is an essential component of well-being and health, being both impaired in aging and disease. Here we review evidence of melanopsin-expressing cell alterations in aging and neurodegenerative diseases and their correlation with the development of circadian rhythm disorders. In healthy humans, the average density of melanopsin-positive cells falls after age 70, accompanied by age-dependent atrophy of dendritic arborization. In addition to aging, inner and outer retinal diseases also involve progressive deterioration and loss of mRGCs that positively correlates with progressive alterations in circadian rhythms. Among others, mRGC number and plexus complexity are impaired in Parkinson’s disease patients; changes that may explain sleep and circadian rhythm disorders in this pathology. The key role of mRGCs in circadian photoentrainment and their loss in age and disease endorse the importance of eye care, even if vision is lost, to preserve melanopsin ganglion cells and their essential functions in the maintenance of an adequate quality of life. View Full-Text
Keywords: ipRGCs; circadian rhythms; aging; retinitis pigmentosa; P23H; Parkinson disease ipRGCs; circadian rhythms; aging; retinitis pigmentosa; P23H; Parkinson disease

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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

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Lax, P.; Ortuño-Lizarán, I.; Maneu, V.; Vidal-Sanz, M.; Cuenca, N. Photosensitive Melanopsin-Containing Retinal Ganglion Cells in Health and Disease: Implications for Circadian Rhythms. Int. J. Mol. Sci. 2019, 20, 3164.

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